I think my biggest issue with identical PC names is they are such an integral way to delineate between players.

If my char's name is Bob, and I want to masquerade as someone else who is also named Bob, I just have to look at them and copy all of their descriptors.

In a real setting, obviously there is much more to masquerading as someone else than just setting a few lines of text to match the other character.

So, there are a number of ways to deal with that, such as player ID's, forcing players to alias names to people, etc. But, I have yet to come up with one that is zero effort, and does not break up the flow of the game, or require players to do some form of OOC action to keep things sorted out.

I just think that allowing player to masquerade as other players to easily can create way to many issues requiring Imm arbitration.